Add debian packaging

Auto configure PAM with pam-auth-update:
  - enable ccreds-check ccreds-save
  - enable krb5

debian/preinst

@@ -0,0 +1,19 @@
+#!/bin/sh
+set -e
+
+case "$1" in
+    install)
+        ;;
+    upgrade)
+        ;;
+    abort-upgrade)
+        ;;
+    *)
+        echo "postinst called with unknown argument \`$1'" >&2
+        exit 0
+        ;;
+esac
+
+#DEBHELPER#
+
+exit 0